The present invention relates generally to field of containers utilized for storing, transporting or processing bulk materials. More specifically, the present invention relates to a bulk cargo container employing a container having a thin elastic shell comprised of fiber reinforced plastic (FRP) supported along its upper edge by a frame assembly, wherein the high tension carrying capabilities of FRP are utilized to support the bulk materials contained within the container. The present invention further relates to a bulk cargo container having one or more hoppers suitable for discharging bulk material contained in the container.
Large containers suitable for storing, transporting or processing solid or liquid bulk materials, especially those containers complying with standards promulgated by the International Organization for Standardization (ISO) [hereinafter ISO containers], have traditionally been fabricated from steel or aluminum panels welded, bolted or riveted together to form a generally box shaped vessel having flat side and bottom walls. Because of the large loads exerted by the weight of the contained bulk material, the panels utilized in constructing the walls and bottom of the vessel must be relatively thick, or must further be reinforced with supporting structure such as ribs, support beams and the like capable of withstanding the large loads applied by the bulk material contained in the vessel. As a result, containers fabricated in such a way tend to be heavy and require a significant amount of labor to fabricate. Seams, crevices and other protrusions formed in the bottom and side walls of the vessel may leak. Further, metals such as steel and aluminum are subject to corrosion, especially when utilized to store or transport corrosive materials such as fertilizers.
Fabrication of large containers of non-metallic materials such as fiber reinforced plastic materials (FRP) offers many advantages over fabrication techniques using steel and aluminum. FRP materials are not subject to corrosion, making it an ideal material for containers utilized to store and/or transport corrosive materials such as fertilizers and the like. Further, FRP materials are substantially lighter than steel or aluminum thereby reducing the weight of the container.
However, the use of FRP materials in the construction of such containers presents many unique problems not encountered with metal containers. FRP materials usually have a lower modulus of elasticity in bending than metals such as steel or aluminum. Consequently, the side and bottom walls of the vessel must be made thicker, and supporting structure such as reinforcing ribs or beams must be provided to support the FRP. Further, the cross-members of this supporting structure must be placed closer together to resist the bending forces to prevent unacceptable deflection which could shatter the FRP. As a result, much of the weight savings realized by using the lighter FRP materials may be lost. Further, because of the increased complexity of such reinforcing structure, the cost of manufacturing FRP containers places them at a cost disadvantage with respect to containers made of steel or aluminum. Nevertheless, because FRP materials are much more resistant to corrosion than steel and aluminum, such materials would be the material of choice for use in manufacturing lightweight vessels and those containing liquids or corrosive materials if the disadvantages associated with its low modulus of elasticity in bending could be overcome thereby eliminating the need for greater material thicknesses and complicated supporting structures.
Present containers do not provide an efficient means for removing bulk materials stored therein. For example, standard ISO containers are loaded and unloaded via doors formed in an end of the container. When solid or liquid bulk material is to be held in such containers, liners may be installed to prevent spillage of the material. Other containers, for example, open-top ISO containers, may comprise tub-like vessels having an open top through which bulk materials can be loaded. The bulk material must then be unloaded through the container""s end doors, if provided, or via the top opening. As a result, unloading of the material from such containers is time consuming and/or may require additional heavy equipment.
Accordingly, the present invention is directed to a bulk cargo container for storing, transporting or processing solid or liquid bulk materials.
In accordance with a first aspect of the present invention, the bulk cargo container is comprised of a vessel having a thin elastic shell comprised of fiber reinforced plastic (FRP) material wherein the high tension carrying capabilities of FRP material are utilized to support the bulk materials contained within the vessel. In one embodiment, the vessel is supported from its upper perimeter via a support member so that the weight of the bulk material contained within the vessel is carried primarily in tension by the FRP material of the vessel""s thin shell. A supporting frame assembly supports the vessel and the bulk material contained therein via the support member. A cover assembly may further be provided for covering bulk material contained within the vessel. The cover may include an arched upper surface having one or more door assemblies for allowing the container to be filled with bulk material.
In accordance with a second aspect of the present invention, the bulk cargo container is comprised of a vessel that includes at least one discharge assembly or hopper having an opening therein suitable for discharging bulk material contained within the vessel. In exemplary embodiments, discharge apparatus such as a conveyor or an auger may be provided for removing bulk material discharged from the hoppers through the openings.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description, serve to explain the principles of the invention.